I have a kotlin class that takes a `suspend` function as a constructor parameter. How can I call thi...

# multiplatform

[adjpd]

I have a kotlin class that takes a suspend function as a constructor parameter. How can I call this in swift? I've attempted to pass a simple closure but it complains it doesn't conform to KotlinSuspendFunction0 . Any idea on the correct swift syntax? My attempt in 🧵.

[adjpd]

kotlin:

class Something(
  val myfn: suspend () -> Unit
) {}

swift: (complains Argument type '()' does not conform to expected type 'KotlinSuspendFunction0')

Something(myfn: { })

[adjpd]

Actually I have something ugly working. Is there not a better way?

class Hmm : KotlinSuspendFunction0 {
    func invoke() async throws -> Any? {
        print("hi?")
    }
}
Something(myfn: Hmm())

[hfhbd]

nope, its not

[adjpd]

It's not what?

Do you mean, there's not a better way?

[hfhbd]

Yes, there is no better way except dont using suspend functions and creating a wrapper for each call... But I prefer a swift class and use Swift 5.5 async.

[adjpd]

Thanks. That sounds annoying. I've not looked at async in swift; I learnt it when it was at version 3 and haven't looked since. Hopefully it'll make the code a little nicer

[hfhbd]

The syntax is nice! But it also has some problems: Currently, you must call a Kotlin suspend function in the "Swift" main thread, but after calling a suspend function, the next calls are on another "Swift" thread...
And Swift does not have an runBlocking method to call async code in non-async block.
And Swift cancelation is not send to Kotlin suspend functions 😄

[adjpd]

Hmm. I'm not that far into it all yet. I don't mind the suspend-function-as-a-callback thing, at least to start with. My main problem now is MainScope() interaction. I thought I'd got around that by simply using suspend methods instead. But now I'm getting the immutable coroutine exception again... Nice technology, but definitely alpha

[adjpd]

Anyway, thanks for your replies. They were really useful